The plywood clamps are Iain Oughtred’s invention. Wedges are driven in to apply the pressure. Not too much pressure is needed with epoxy joints, just enough to keep the pieces together while the epoxy sets.
The strakes were cut with a hand held jigsaw following a line drawn from a full sized “door skin” pattern, 1/8th inch plywood that was first clamped to the molds for marking and cutting. Each pattern needed reclamping and remarking and adjusted cutting until it fit its marks on the molds. This is a neat process, proceding from the plans on paper to marks on molds to an actual pattern. If the molds you make are slightly off, the boat planks will also be slightly off, but the boat will still float. If you tried to cut all the curved planks first and then fit them together, you’d probably end up with a real mess.